This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from my application entitled APPARATUS FOR FORMING THIN FILM USING MICROWAVE AND METHOD THEREFOR filed with the Korean Industrial Property office on the Dec. 31, 1997 and there duly assigned Ser. No. 97-82049 by that Office.
1. Field of the Invention
The present invention relates to an apparatus for forming a thin film and a method therefor, and more particularly, to an apparatus for forming a thin film using microwave and a method therefor.
2. Description of the Related Art
Flame hydrolysis deposition (FHD), chemical vapor deposition (CVD), modified chemical vapor deposition (MCVD), physical vapor deposition (PVD), sputtering, e-beam evaporation deposition, and a spin coating method are generally used to form a thin film on a wafer. The thickness, the deposition speed, and the density of the thin film are controlled according to variables such as materials used, mixture of materials, velocity of a moving fluid, temperature, plasma output, voltage, and rotation number when the thin film is deposited using the above methods.
In one method of manufacturing a thin film according to a conventional flame hydrolysis deposition (FHD) method, silica soot is formed on a wafer using the FHD method. When the film is formed by the FHD method, it is necessary to undergo a high temperature thermal process. The high temperature thermal process is performed using a resistance heating furnace. The high temperature thermal process is for densifying the soot. First, the wafer and the soot are heated at a temperature of between about 800xc2x0 C. and 1,350xc2x0 C. The temperature is maintained for one to three hours. The thin film is formed through a cooling process.
In the processes of manufacturing the thin film according to the above FHD method, the process of densifying the soot by a resistance heating method is lengthy. It takes four to six hours to heat the soot and the high temperature is maintained for one to two hours. It takes about 15 hours overall to heat the soot, to maintain the high temperature, and to lower the temperature from above 800xc2x0 C. to room temperature. Since a heating source such as a resistance heating furnace delivers heat from outside a sample (the wafer and the soot thereon) to be heated, the temperature outside of the sample rises faster than that inside of the sample. Accordingly, the temperature of the surface of the stacked soot becomes higher than the temperature of an interface which contacts the soot and the wafer. Gas which is not emitted to the outside due to a difference of temperatures between the surface of the soot and the interface layer may form blisters inside the soot layer. Also, when a multilayer film is formed using the resistance heating furnace, heat at the same temperature is applied to the wafer, the previously formed films, and the entire soot to be newly densified. Accordingly, cracking due to thermal stress may occur between films of different components.
It is therefore an object of the present invention to provide an improved apparatus and method for forming thin films on a wafer.
It is a further object of the present invention to provide an apparatus and method which allow for faster densification of a thin film.
It is a yet further object of the present invention to provide an apparatus and method in which blistering of the film during thermal treatment is prevented.
It is a still further object of the present invention to provide an apparatus and method in which cracking of the film due to thermal stress is prevented.
To achieve the above objects, the present invention provides an apparatus and a method for forming a thin film using microwave in which the film is rapidly densified using microwave radiation as a heating source when a single layer film or a multilayer film is formed on a wafer. Accordingly, an apparatus for forming a thin film on a wafer by densifying predetermined soot on a wafer, when the wafer and the soot form a sample, includes a microwave sintering furnace for sealing the sample and exposing the sample to microwave, thus sintering the sample, a sintering furnace atmosphere maker for controlling the state, being the atmosphere of air inside the microwave sintering furnace, a temperature sensor/controller for sensing a temperature inside the microwave sintering furnace, comparing the temperature with a predetermined reference temperature, and outputting an error temperature, and a microwave power source for generating microwave of a predetermined temperature with reference to the error temperature output from the temperature sensor/controller and applying the microwave to the microwave sintering furnace.
The sintering furnace atmosphere maker preferably can evacuate the inside of the microwave sintering furnace. The microwave sintering furnace atmosphere maker preferably can provide an atmosphere of a predetermined component to the microwave sintering furnace.
The microwave sintering furnace preferably includes an insulating material surrounding the sample in order to prevent heat from being emitted in a process of densifying the soot. The insulating material is preferably a high temperature ceramic insulating material.
It is preferable that the microwave sintering furnace further includes a predetermined supporter connected to the temperature sensor/controller for supporting the sample inside the insulating material.
A method for forming a film on a wafer using microwave includes the steps of manufacturing soot of a predetermined component on a wafer, heating the soot by applying microwave, maintaining the temperature of the heated soot for a predetermined time, and completing the film by cooling the soot. The soot is preferably a silica soot.